U-T Multimedia

SAN DIEGO – The Steve Gregory experiment having worked out in its first incarnation, Norv Turner this week made a point to portray the switch at the nickel back position as a sort of change of scenery for all involved.

“When you make a move like we did, you can either look at it and say it's a positive move for Steve Gregory and our football team,” the Chargers head coach said, “or you say it's a negative because we've moved someone.”

Antoine Cason, while determined to accept the former, seethes quietly. He most definitely sees the latter much clearer.

“I don't know what the thinking is behind it,” said Cason, who has yet to be told why he lost his job at the No. 1 nickel spot.

Gregory on Sunday in Kansas City intercepted a pass, had a sack, two passes defensed (one of which should have been another pick), a quarterback knockdown and a hurry.

Albeit playing a team with a harried quarterback and anything but elite receivers, Gregory looked comfortable and aware of what he needed to do.

On one play in the third quarter, he defied an attempt to block him out of a play because he clearly knew where the ball was going. On another play, he blitzed and then came back to make the tackle after a short gain. He had one pass caught on him in the five times he was targeted.

“Steve has a real good change of direction, real good suddenness, and he's suited to play in the slot,” Turner said. “ ... He's more experienced (than Cason). He understands what people are doing in there. He's very quick, a compact player.”

Chargers coaches have said publicly over the past week the move was about Gregory being better suited to play in the slot, where the nickel back has to play in space, more than Cason having done something wrong. Cason was drafted in the first round in 2008 as a cornerback and is seen as a future starter at that position.

“I'm a big Cason guy, and I think he's an outstanding corner,” Turner said. “I think we've taken some pressure off him, and he can be prepared to back up both our corners on the outside.”

But sources said coaches had been trying to motivate Cason to improve and that they felt it hadn't happened. He also made a couple mistakes in the Denver game that may have prompted the move, more than a week (and a game) after Gregory had started working in as the No. 1 nickel in practice.

Cason, whose two interceptions lead the team, is clearly still reeling. He spent hours last week assessing his situation and trying to figure out what he did wrong.

“I depended on the coaches to dictate to me how I'm going to play without playing like I did to get here,” said Cason, who at Arizona in 2007 was the Thorpe Award winner as the nation's top collegiate defensive back. “ . . . No one can teach me to play with instincts. It's on me to go out and make plays.”